Not only are these spammers total IDIOTS (the URLs aren't hyperlinked, so they get no SERP power, and none of my site visitors are going to copy/paste a link from text into their address bar) but they are also SUPER persistent!! I'm talking hundreds of threads per hour!
A couple of my smaller sites were hit with Korean spam today at 4 am. Here's what I did to stop them:
First I bumped up the registration block in TPU Spam Detect (LOVE THIS PLUGIN) to limit Philipines, Hong Kong, China
Next, I looked at 3 examples of the current spam and found characters that are very common. I then went into Spam Management, and for "Spam Phrases" and added them with wildcards!
So, this should catch a bunch of the Korean spam that comes in. I can add more characters if we see even more trends in what's used by these spammers.
For sanity, I dug up some of the foreign spam I had back in October when I started this thread and almost all the characters above were represented somewhere in those old posts too!
So, I'm pretty confident that this is going to work really well, at least for keeping the Korean spam from touching my live forum!
Here's an example of the junk text / characters they post: